At present, most hazardous and toxic liquids are stored in metal drums or, where smaller quantities are involved, in plastic containers. Hazardous or toxic compounds, such as agrochemical compounds, are formulated in various compositions.
The expression toxic or hazardous compounds as used herein means an industrial chemical or agrochemical compound, which, if released in the quantity or concentration normally present in storage and shipping containers, may cause damage to the environment or be injurious to a person contacted by it.
With respect to agricultural chemicals, liquid compositions, particularly in the form of concentrates, are most convenient for farmers because of the relative ease with which they can be handled, formulated and used. However, there are significant difficulties in handling such liquid compositions.
There is a danger of spillage or leakage if holes develop in the containers or if containers are accidentally dropped and thereby crack or fail. Containers have been developed which possess great resistance to impact and shock. While such containers are secure under normal storage and handling conditions, in the event of an accident, for example during transporting, there remains an appreciable risk of spillage or leakage with rapid loss of liquid. Leakage of toxic and hazardous chemicals can create damage to the environment.
The chemical and packaging industries have long sought a secure container which provides sufficient safeguards for those handling it, such as farmers and transporters, as well as adequate protection for the environment.
It is known, for example, to package agrochemicals in soluble bags or sachets made from films. However, such films may crack and break and thus cause leakage of the agrochemical contents. There are a variety of defects which can occur in films, which may lead to weaknesses of the film and become a potential source of leakage. For example, the presence of air bubbles, dust particles or foreign bodies in gel particles or the existence of thin points on or in the film are all potential weak points. If a film with such a weak point is subjected to a lot of handling or physical shock, the film may fail at a weak point. This is especially a problem in the agrochemical industry where containers may be subjected to repeated and uncontrolled handling by distributors, transporters or farmers.
In other industries such as pharmaceuticals and cosmetics, gel formulations have been used as a means for packaging pharmaceutical or cosmetic products. However, such gel formulations are often utilized for aesthetic and other reasons and not as part of a containerization system for holding and securing toxic or hazardous chemicals. Furthermore, the gels used for pharmaceutical or cosmetic purposes are generally waterbased.
Another possibility is to provide agrochemicals in the form of wettable powders which can be contained within a bag which may be water soluble or water dispersible. However, when wettable powders are placed in water soluble bags and then added to water in spray tanks, the bag floats because the bulk density of the product is low. As the bag floats in the spray tank, it can become attached to either the side of the tank or recirculation piping within the tank. This is because the materials used in water soluble bags, such as polyvinylalcohol, tend to be sticky and become a very good adhesive when wet. The longer it takes to get the bag to dissolve, the higher the probability that the bag will adhere to some part inside the spray tank. Another problem is that as the bag dissolves and releases the powder, some powder gets bound to the bag and does not disperse. Also, in view of its relatively low density, the bag floats above the water level in the tank which further inhibits full dissolution of the bag. This problem can build up over time and cause numerous problems due to filters getting clogged by either undissolved bag or wettable powder that has not been properly wetted and which becomes stuck to the filter system of the spray tank or the spray nozzles. This causes serious problems since the farmer/applicator must clean this up, potentially exposing himself to the chemical itself.
Also suggested have been containing systems for pesticides in which the liquid-containing active ingredient is enclosed within soluble bags or sachets. However, the bags tend to develop pinholes and the contained liquid leaks under such conditions causing potential injury to the environment.
It has also been proposed for pesticides to be packaged in soluble bags or sachets which contain an air space to absorb shocks and to avoid leakage. This feature does tend to reduce bag failure. However, this does not avoid the problems of pinholes. Also, this approach has a disadvantage in that such bags cannot effectively be used as a self-dispensing container. The specific gravity of liquid and the included air space, causes such a bag to float and not to become immersed when placed in a spray tank. As a result, there is incomplete contact between water and the bag which is not adequate for rapid dissolution.